Mediastinal lymph node sampling following positron emission tomography with fluorodeoxyglucose imaging in lung cancer staging.

OBJECTIVES: To evaluate the predictive accuracy as well as the rates of false-positive and false-negative results of CT and positron emission tomography (PET)-fluorodeoxyglucose (FDG) imaging in detecting the metastatic intrathoracic lymph nodes in patients with suspected or proven non-small cell lung cancer (NSCLC). Our other objective was to determine the need for routine invasive sampling procedure in confirming PET/CT staging results. METHODS: The results of CT and PET-FDG scanning in 77 patients with suspected or proven NSCLC were correlated with the histologic findings of hilar/mediastinal lymph node sampling using mediastinoscopy, open biopsy, thoracotomy, or thoracotomy with resection. Patients were then classified into resectable and unresectable groups based initially on PET results and compared to histologic findings. RESULTS: The sensitivity, specificity, and accuracy of CT and PET for detecting metastatic lymphadenopathy were 68%, 61%, 63%, and 87%, 91%, and 82%, respectively. A change of management with routine sampling following PET was seen in five of six patients (83%) with false-positive findings (13%) but in none of four patients (9%) with false-negative findings. CONCLUSION: The false-positive findings of PET-FDG imaging affected selection of treatment in 83% of patients. However, false-negative results did not change management in any patient. This could potentially prevent unnecessary invasive thoracotomy, mediastinoscopy, or other sampling procedures in patients with negative PET results.

Positron emission mammography-guided breast biopsy.

UNLABELLED: Positron emission mammography (PEM) is a technique to obtain planar images of the breast for detection of potentially cancerous, radiotracer-avid tumors. To increase the diagnostic accuracy of this method, use of minimally invasive methods (e.g., core biopsy) may be desirable for obtaining tissue samples from lesions detected with PEM. The purpose of this study was to test the capabilities of a novel method for performing PEM-guided stereotactic breast biopsies. METHODS: The PEM system consisted of 2 square (10 x 10 cm) arrays of discrete scintillator crystals. The detectors were mounted on a stereotactic biopsy table. The stereotactic technique used 2 PEM images acquired at +/-15 degrees and a new trigonometric algorithm. The accuracy and precision of the guidance method was tested by placement of small point sources of (18)F at known locations within the field of view of the imager. The calculated positions of the sources were compared with the known locations. In addition, simulated stereotactic biopsies of a breast phantom consisting of a 10-mm-diameter gelatin sphere containing a concentration of (18)F-FDG consistent with that reported for breast cancer were performed. The simulated lesion was embedded in a 4-cm-thick slab of gelatin containing a commonly reported concentration of FDG, simulating a compressed breast (target-to-background ratio, approximately 8.5:1). An anthropomorphic torso phantom was used to simulate tracer uptake in the organs of a patient 1 h after a 370-MBq injection of FDG. Five trials of the biopsy procedure were performed to assess repeatability. Finally, a method for verifying needle positioning was tested. RESULTS: The positions of the point sources were successfully calculated to within 0.6 mm of their true positions with a mean error of +/-0.4 mm. The biopsy procedures, including the method for verification of needle position, were successful in all 5 trials in acquiring samples from the simulated lesions. CONCLUSION: The success of this new technique shows its potential for guiding the biopsy of breast lesions optimally detected with PEM.

Clinical utility of PET-FDG imaging in differentiation of benign from malignant adrenal masses in lung cancer.

This study was designed to evaluate the sensitivity, specificity, and predictive accuracy of PET-FDG imaging in detecting metastatic disease involvement of adrenal glands in patients with lung cancer. We wanted to compare efficacy of positron emission tomography (PET)-fluorodeoxyglucose (FDG) imaging to computed tomography (CT) scanning in differentiating benign from malignant involvement of adrenal glands in patients with lung cancer. Thirty patients with biopsy-proven lung cancer and abnormal findings on PET and/or CT scanning were studied for presence of adrenal abnormality suggestive of metastatic disease involvement (n = 26) or benign adrenal enlargement (n = 4). The results of PET and CT scanning were compared to histological findings and/or clinical follow-up for at least 1 year for presence or absence of adrenal metastases. PET-FDG imaging correctly detected the presence of metastatic involvement in 17 of 18 patients and excluded metastatic involvement in 11 of 12 patients for sensitivity, specificity, and accuracy of 94.4%, 91.6%, and 93.3%, respectively. CT scanning showed enlarged adrenals without metastases in 8 of 30 patients and normal-sized adrenals in the presence of metastases in 5 of 30 patients. There was a false-positive PET finding in 1 patient and a false-negative PET finding in another patient. PET-FDG imaging is a highly sensitive, specific, and accurate test to differentiate benign from malignant involvement of adrenal glands in patients with lung cancer and often ambiguous findings on CT scanning.

The potential role of positron emission mammography for detection of breast cancer. A phantom study.

Positron emission mammography (PEM) is a new, specialized imaging modality utilizing PET radiopharmaceuticals to detect breast cancer. The capabilities and limitations of PEM in detecting breast tumors were investigated with a series of phantom experiments. The PEM imager was mounted on a standard Lorad biopsy table (separated by 18 cm). In the initial phase of the investigation, basic scanner parameters (resolution, sensitivity, and scatter fraction) were measured. The effects of a number of breast imaging parameters (length of acquisition, breast thickness, and breast density) on detection of breast lesions were then explored utilizing special phantoms. Moderately compressed breasts were simulated with a block of gelatin containing amounts of FDG consistent with 370 MBq injections. Lesions were simulated with four hollow spheres (inner diameters=5 mm, 8 mm, 12 mm, and 15 mm) filled with amounts of FDG representative of uptake in malignant breast tumors (target-to-background concentration ratio=8.5:1). Resolution at the center of the imager was 3.9 mm, sensitivity was 0.059 kcps/kBq/ml and the Compton scatter fraction was approximately 12%. Objects as small as 8 mm in diameter could be detected after 30 s of data acquisition; 5 mm spheres were detectable after 300 s. Object detection capabilities were reduced with increasing breast thickness. In thin compressed breasts (2 cm) even the smallest sphere (5 mm in diameter) could be detected; increasing breast thickness increased the minimum detectable sphere diameter to 8 mm. Increased background activity caused by FDG uptake in metabolically active normal tissue more prevalent in radiodense breasts compared to "fatty" breasts was simulated and shown to reduce the minimum detectable lesion size to 12 mm for the densest breasts. These results demonstrate the potential of PEM for the detection of breast lesions. The addition of the system to a standard biopsy apparatus indicates its potential for use to guide some core biopsies of breast cancers.

Comparative efficacy of positron emission tomography with fluorodeoxyglucose in evaluation of small (<1 cm), intermediate (1 to 3 cm), and large (>3 cm) lymph node lesions.

PURPOSE: Our objective was to determine if positron emission tomography (PET) with fluorodeoxyglucose (FDG; PET-FDG) imaging is equally efficacious in detection of metastases in small and large mediastinal lymph nodes as compared to CT scanning. MATERIALS AND METHODS: PET-FDG imaging, CT scanning, and histology results of sampled mediastinal lymph nodes were compared in 54 patients of total 118 patients studied. Efficacy of PET and CT was determined and compared in small (< 1 cm), intermediate (1 to 3 cm), and large (> 3 cm) mediastinal lesions. RESULTS: PET was accurate in 94% of patients in characterizing "N" disease as compared to 61% with CT. Overall, sensitivity, specificity, and accuracy of PET for staging mediastinal lymph nodes (n = 168 in 54 patients) was 96, 93, and 94%, as compared to 68, 65, and 66% with CT. Positive and negative predictive value of PET in detecting mediastinal adenopathy was 86% and 98%, as compared to 47% and 82% with CT, respectively. PET was also highly reliable and accurate for detecting lymph nodes < 1 cm, 1 to 3 cm, and > 3 cm in size with superior efficacy than CT. Sensitivity, specificity, and accuracy of PET for detecting malignancy in lymph node lesions < 1 cm in size was 97, 82, and 95%, respectively. CONCLUSION: PET-FDG imaging is equally reliable and accurate for detecting disease in small and large lymph node lesions in patients with suspected or proven lung cancer with better efficacy than CT.

Treatment outcome of lung cancer patients as optimized by preoperative whole-body positron emission tomography fluorodeoxyglucose imaging.

Positron emission tomography (PET) fluorodeoxyglucose (FDG) imaging may be more accurate than computed tomography (CT) scanning for staging of lung cancer disease. In the present study, we evaluate whether whole-body PET-FDG imaging can accurately stratify lung cancer patients by stage and thus predict patient outcome. Forty-one consecutive patients underwent whole-body PET and CT scanning for preoperative staging, which was then confirmed by mediastinoscopy, thoracotomy, and/or other tests revealing distant metastases. The effect of PET on patient management was determined. PET was significantly more accurate than CT for staging of lung cancer (97.6% vs. 70.7%). One-year follow-up for survival rate and treatment response was also compared in different patient groups. PET accurately identified patients with resectable disease (Group A). Group B patients, with medically inoperable disease, and Group C patients, with unresectable advanced disease, had 100% and 53% incidence of adverse events (defined as recurrence, evidence of new disease, or death), respectively. Group A patients with resectable disease who underwent surgery showed the best patient outcome, with only 7% incidence of adverse events. In conclusion, whole-body PET can be useful in identifying a group of lung cancer patients with resectable disease most likely to benefit from surgical resection. Further studies are needed to explore whether PET can predict patient outcome of various lung cancer patients receiving different treatment regimens.

Comparative efficacy of positron emission tomography with FDG and computed tomographic scanning in preoperative staging of non-small cell lung cancer.

OBJECTIVE: To determine the sensitivity, specificity, and accuracy of positron emission tomography with 2-fluorine-18-fluorodeoxyglucose (PET-FDG) in the preoperative staging (N and M staging) of patients with lung cancer. The authors wanted to compare the efficacy of PET scanning with currently used computed tomography (CT) scanning. MATERIALS AND METHODS: Results of whole-body PET-FDG imaging and CT scans were compared with histologic findings for the presence or absence of lymph node disease or metastatic sites. Sampling of mediastinal lymph nodes was performed using mediastinoscopy or thoracotomy. RESULTS: PET-FDG imaging was significantly more sensitive, specific, and accurate for detecting N disease than CT. PET changed N staging in 35% and M staging in 11% of patients. CT scans helped in accurate anatomic localization of 6/57 PET lymph node abnormalities. CONCLUSION: PET-FDG is a reliable method for preoperative staging of patients with lung cancer and would help to optimize management of these patients. Accurate lymph node staging of lung cancer may be ideally performed by simultaneous review of PET and CT scans.